Kevin Toolis, a director and co-founder of independent producer Many Rivers Films, which makes investigative films for BBC1's Panorama and Channel 4's Dispatches, blamed financial pressures for this dwindling commitment.

"I did a commission a couple of weeks ago for the Sunday Times magazine with a very, very distinguished photographer, and you'd be amazed at how little he was paid," Toolis told a panel at the Sheffield Doc/Fest today.

"The Sunday Times – one of the most powerful, richest media institutions – just no longer sends people abroad; it'll use its own people. But then you will not have same engagement of media professionals trying to undercover something, because it takes money and time – you have to send people, pay for it. The commitment to spending money on this stuff is dying a death."

David Henshaw, the managing director of Hardcash Productions, which produces films primarily for Dispatches, also said the BBC and other UK broadcasters – aside from Channel 4 – need to be more robust in backing "difficult" investigative programming.

"What we need is broadcasters and proprietors who are prepared to back difficult journalism, and it is a disgracefully expensive process," he told the panel.

"Recently Channel 4 have had an extremely robust attitude with the stuff they've commissioned, and have backed it up – when you look at some other broadcasters, including the BBC, and you want to make the same kind of difficult dangerous exposé programme, you're probably more on your own."

Henshaw, who directed BBC1's controversial 1989 undercover series on racial discrimination Black and White, suggested that the corporation would have cowed to legal pressure and not broadcast the programme in the current climate.

"What was great about the BBC was that Jonathan Powell – who was the controller for BBC1 at the time – looked at it and said this is important social material, it's got to be out there. The BBC did broadcast – whether they'd do that now, I'm not so sure," he said.

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